Differential tremulant



Patented Mar. 31, 1953 UNITED STATES PATENT OFFICE DIFFERENTIAL TREMULAN T Lake, N. J.

Application March 31, 1952, Serial No. 279,613

i This invention relates to improvements in reservoirs for pipe or reed organs and more particularly to a differential tremulant therefor.

As described in my copending application Serial Number 278,048, filed March 22, 1952, and entitled Reservoir for Pipe or Reed Organs, I have provided an improved reservoir inter onnected between the air compressor and the sound box whereby the static pressure of the wind is reduced to the desired regulated wind on which the pipe speaks. In such construction, I have provided an improved spring and pulley arrangement for most effective equalization.

In accordance with my present invention I have provided a modified form of reservoir whereby I can produce a differential tremulant for such pipe or reed organs by a pneumatic or equivalent valve control within the reservoir. While this modified reservoir may be especially effective with the invention as disclosed in the above entitled patent application, the benefits may be generally obtained whether the expansion board movement is controlled by a spring orby weights.

With the improved form of tremulant control as above considered, I am enabled to obtain a further benefit in that the frequency of the tremulant may be readily-varied by a valve adjustment so that unusual effects for reed and pipe organs may be obtained.

Further objects and advantages of my invention will appear from the following description of a preferred form of embodiment of my invention taken in connection with the drawing attached, such drawing being a generally central vertical section through a reservoir of the type described.

The single figure shows a generally central vertical section through a reservoir for an organ.

As more particularly shown, the reservoir is a generally rectangular box In having a wind inlet [2 which is in communication with a suitable blower not shown, and having a wind outlet It in communication with the organ chest, also not shown. The reservoir has the expansion board It connected by suitable bellows diaphragms 18 so that the volume of the reserovir can be changed.

To effectively vary the pressure and volume of the wind with the requirements of the pipes, I may provide an equilibrium valve which is interconnected by cable with the expansion board l6, such cable passing over a pulley as shown in my copending application. In addition, one or more springs, adjustably anchored to the wall of the reservoir box Ill and connected on the other end to the expansion board IE or weights, not shown, may be used to counteract the wind pressure.

Within the reservoir I I provide a valve struc- 4 Claims. (01. 84348) ture consisting of chambers of predetermined volume and interconnected by valved passages whereby the normal regular expansion and contraction of the expansion board it can be made to tremulate. This internal valve structure is generally indicated at 30 and is connected to the expansion board by supplemental bellows diaphragm members Illa. This construction now divides the interior of the reservoir into normal reservoir compartment A and control compartment B. The effective area of the control compartment is indicated at 32.

Within the valve structure 30, I also provide separate chambers 36 and 36 the first of which is in communiction with the control compartment B through passage 38, through valved opening 46 and valve 42 operated by diaphragm M.

Valve 62 also can be moved into a position to close normally open passage 46 to compartment A. The chamber 34 has an opening 48 to atmosphere.

Chamber 36 also has an opening to atmosphere shown at 50 and has a valve 52 tending to close opening 54 to compartment A. Valve 52 is operated by a diaphragm 56 in communication with passageway 38 in which is control valve 58. Diaphragm 56 also controls valve 55.

The efiective pressure in chamber 36 directly controls the movement of valve 52 by being interconnected through passage 50 with the actuating diaphragm 44.

In operation, with valve 42 in the normal posi-= tion, closing opening til, the tremulant is inactive for the wind pressure in compartment A is the same as in compartment B (through passageway 38 and valve opening 46).

With valve 58 in the open position however, the wind in compartment A becomes effective on diaphragm 56 which lifts valve 52 from its seat. This permits the reservoir pressure in chamber A to pass through channel 54 and Gil to become active on diaphragm M. This in turn raises valve 42 to shut oii the wind through opening 55 and passage 38 to diaphragm 56. At the same time the wind pressure in chamber B passes into chamber 34, which being connected to the atmosphere through opening 43, will immediately reduce the pressure in chamber B to atmospheric.

When the pressure in chamber B is atmospheric, the active reservoir area is no longer the entire cross section of expansion board it, but rather the total area less the area of the expansion board 16 corresponding to its width times the length portion 32. This may be represented by the effective area of A minus the eiiective area of B.

Since the pressure on the wind in compartment A is a function of the tension of the springs (or equivalent weights) acting on expansion board 16, divided by the cross section of the expansion board, the reduction in effective area of the expansion board will immediately cause a rise in the Wind pressure in chamber A. Therefore, if chamber B is alternately filled with reservoir pressure and then depressed to atmosphere, the effective pressure in the reservoir 12'] will vary and. cause the sound to tremulate.

It will be appreciated that the raising of valve 42 in sealing of the opening 46 not only stops flow of wind from the pressure in chamber A and causes Wind to pass from chamber B to atmosphere, but immediately on the chamber 36 is again in communication with the "atmosphere through opening 50. This may be quite small-as the only volume is that of the chamber itself, t e assa e 5. a t p a m is. Va ve 5. of course prevents flow from passage 50 when in the upper position.

The frequency of the operation is controllable by the size of the opening of valve 58. The rate at which diaphragm 56 fills is of course dependent upon the size of this opening. Therefore the, rate at which valve 52 rises is dependent upon the size of the opening of valve it and in turn the rate of lifting and lowering of valve 12 is directly controlled by this control valve 58 In' thepr efer'red construction, the dilierential pressure chamber B is mounted within the reservoir 'A and periodicallyv diminishes or enlarges the" active size of the movable expansion board of the reservoir and thus periodically amplifies or weakens'the effect of the spring or weight power'exerted on the expansionboard. It will thus appear that a similar effect can be obtained if the differential pressure chamber is mounted external of the reservoir and one or more chambers may be used. It will also be apparent that the desired effects may be obtained whether the pressure of the differential chamber is supple-i mental to or opposed to the effective pressure of the reservoir.

I claim:

1. In a reservoir for reed andpipeorganshav- 4 ing a primary wind equalizing chamber, and a secondary wind chamber, an expansion board to vary the volume of said chambers in accordance with wind demand, and means to impress a tremulant effect on the effective wind pressure which comprises a first valve, a pilot valve, a control valve, and interconnected passageways whereby opening of the control valve will cause primary wind action on the pilot valve, movement or said pilot valve causing movement of the first valve, said first valvemovement depressuring the secondary wind chamber and simultaneously shutting off the wind to the pilot valve, the depressuring of the secondary wind chamber causing a sudden rise the effective wind pressure in the reservoir.

2. In a reservoir for reed and pipe organs as claimed in claim 1, of means to set the size of the opening in the control valve whereby the frequency of the tremulant effect is modified.

3. A reservoir for reed and pipe organs which has a wind inlet, a wind outlet, a primary wind equalizing chamber, an expansion board, means to maintain a substantially constant pressure in said primary wind equalizing chamber, and a differential pressure. control means acting on said expansion board, interlocking control devices to vary the differential control means periodically whereby a tremulant effect is impressed on the windv outlet.

4. A reservoir for reed and pipe organs as claimed inclaim 3 in which means are provided for varying the frequency of the. variation o the differential control means.

JOSEPH GLATTEReG'IZ.

BEEEBE GES: Ql ED;

The following references are of record in; the file of: this patent:

N TED ST TE A NTS.

Numb Nam D te 478,552 Bassett; July 12 1892. 1,619,53 N man- -,-l -.,-c-- r 1 1 

